Production of gamma-butyrolactone from maleic anhydride with a hydrogenation catalyst

ABSTRACT

Hydrogenation catalyst and a process for producing gamma-butyrolactone by hydrogenating a feed compound -- selected from the group consisting of maleic acid, succinic acid, maleic anhydride, succinic anhydride, and mixtures of any of the foregoing -- in the vapor phase, in the presence of said catalyst, which is a highly selective elemental Cu-Pd or Cu-Pt catalyst, in order to produce high yields of gamma-butyrolactone and minimize the formation of by-products.

This is a division of application Ser. No. 716,111, filed Aug. 20, 1976.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to improved hydrogenation catalysts, amethod of producing such catalysts, and to the production ofgamma-butyrolactone with such catalysts from maleic acid, succinic acid,maleic acid, succinic acid, maleic anhydride, succinic anhydride, andmixtures thereof, and, more particularly, relates to highly selectivehydrogenation catalysts comprising elemental Cu-Pd or Cu-Pt, a method ofproducing such catalysts, and an improved process for the production ofgamma-butyrolactone by catalytically hydrogenating, in the vapor phase,a feed compound selected from the group consisting of maleic acid,succinic acid, maleic anhydride, succinic anhydride, and mixtures of anyof the foregoing with or without butyrolactone, in the presence of saidhighly selective hydrogenation catalysts.

2. Description of the Prior Art

Gamma-butyrolactone is a stable, well known compound that is a liquidat - 44° C. to 204° C. It is preferably used as an intermediate, e.g.,in the manufacture of 2-pyrrolidone, α-tetralone, glutaric acid, etc. Itis also useful in the solvent welding of plastic films; as a swellingagent for cellulose acetate films; and as a non-corrosive solvent forpolymers in general, acetylene, and water-immiscible alcohols.

In general, the catalytic hydrogenation of maleic anhydride and/or otherrelated compounds to produce gamma-butyrolactone (hereinafter referredto as "butyrolactone") is an old and well established art for which agreat many processes have been used, the most important of whichhistorically have been effected in the liquid phase.

Exemplary of such liquid phase processes are U.S. Pat. Nos. 2,772,291-3,which generally relate to high pressure hydrogenation of maleicanhydride to form various mixtures of butyrolactone, tetrahydrofuran,and butanediol in the presence of such catalysts as those ofnickel-chromium-molybdenum, Raney-type nickel or cabalt, and nickel orcobalt molybdates. Later patents utilizing liquid phase, catalysthydrogenation of conventional feedstocks, such as maleic anhydride, tobutyrolactone have substantially dealt with modifications of those typesof catalyst. For example, U.S. Pat. No. 3,312,718, relating generally tosubstantially complete conversion of succinic anhydride tobutyrolactone, employs a hydrogenation catalyst, preferably of nickel,along with a silicotungstic acid as promoter.

Additionally, U.S. Pat. No. 3,113,138 discloses processes utilizingpalladium catalysts, in the liquid phase, together with certainsolvents, to obtain butyrolactone from succinic anhydride, but processessuch as these have been characterized by a short catalyst life and havebeen unable to provide adequate yields.

An alternative to the commercially-used, liquid phase catalytichydrogenation of maleic anhydride, succinic anhydride, etc., feedstocksessentially consists of vapor phase hydrogenation, at low pressures, inthe presence of a generally different class or type of catalyst, butthere has been much less activity in this area in general, and processesusing vapor phase catalytic hydrogenation have not heretofore foundcommercial favor. Exemplary of patents covering vapor phase catalytichydrogenation of conventional feedstocks to butyrolactone include, forexample, U.S. Pat. No. 3,065,243, wherein the conversion tobutyrolactone is effected at low pressure in the presence of a copperchromite catalyst. Later work in this field has included variouscatalyst modifications utilizing, e.g., different combinations ofcopper, chromium, and zinc, whereby, in some instances, Cu-Zn has beenused; in other instances, a combination of Cu-Cr has been used; and,finally, in another combination, that of Cu-Cr-Zn has been used.Exemplary of this later work is U.S. Pat. No. 3,580,930, which describesthe use of Cu-Cr-Zn.

In addition, among other conventional hydrogenation catalysts, there maybe mentioned catalysts containing such metals as rhenium and rhodium,but neither of these is presently used for hydrogenation reactions ofthe type described herein and neither would be as acceptable as thecatalysts previously described above.

However, commercial practice in respect of the production ofbutyrolactone from conventional maleic anhydride, succinic anhydride,etc., feedstocks by catalytic hydrogenation has not been entirelysuccessful, especially in terms of both high activity and high yield.The present invention has been developed to fill this void, and provideselemental Cu-Pd and Cu-Pt catalysts, which not only retain theselectivity shown by copper alone without additives, but also have anactivity much greater than that afforded by copper alone.

SUMMARY OF THE INVENTION

The present invention, as previously noted, is directed to improvedhydrogenation catalysts, a method of producing same, and to an improvedprocess for obtaining butyrolactone by catalytically hydrogenating, inthe vapor phase, a feed compound, preferably one selected from the groupconsisting of maleic acid, succinic acid, maleic anhydride, succinicanhydride, and mixtures of any of the foregoing, in the presence of thehighly selective hydrogenation catalysts containing metals of bothcopper and palladium or both copper and platinum and having a specificcomposition as hereinafter defined.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present catalyst composition is one that is characterized bydisplaying, in addition to a very long active life, an activity of amuch higher order of magnitude than either copper alone or in variousadmixtures with chromium and/or zinc, the materials previously used topromote the activity of copper. Furthermore, the present elementalCu-Pd-, and Cu-Pt-containing catalysts are also capable of retaining thehigh selectivity of copper without additives, a feature to be contrastedwith the fact that use of other hydrogenating additives, such as nickeland cobalt, which display high activity as hydrogenation catalysts, inthe present catalysts, results in a decrease in selectivity. Similarly,other highly active hydrogenation catalysts such as ruthenium andrhodium are likewise unsatisfactory.

While the present feedstocks may contain both a carbonyl group and asite of ethylenic unsaturation, and while hydrogenation ordinarily isknown to add to both such moieties under different conditions, normallyin two separate steps, nevertheless, in view of the outstandingly highdegree of selectivity and activity of the present Cu-Pd-, andCu-Pt-containing catalysts, hydrogenation of both the carbonyl group andthe site of ethylenic unsaturation can essentially be conducted in asingle stage.

Maleic acid has the same skeletal structure as succinic acid and isknown to yield the latter on catalytic hydrogenation. Succinic acid, inturn, readily forms the corresponding anhydride, one carbonyl group ofwhich can be reduced, under carefully controlled hydrogenationconditions to form butyrolactone. Thus, it can readily be seen that allof the present starting materials are individually convertible tobutyrolactone by catalytic hydrogenation and that the formation ofbutyrolactone from any of such materials or mixtures thereof, is afunction of the degree of hydrogenation each of such starting materialsrequires during catalytic hydrogenation, such function itself beingreadily within the manipulative skill of the operator, based upon use ofparticular combinations of feed rates, mole ratios of reactants,temperatures, reaction times, reactor sizes, etc., as desired. In anyevent, all of the present feedstocks, with the exception of succinicanhydride, are presumably converted to succinic anhydride, the immediateprecursor of butyrolactone which, upon further catalytic hydrogenation,is converted to butyrolactone. When the feedstocks, however, are maleicor succinic acid, it is preferable that such feedstocks be firstdehydrated at elevated temperatures to the corresponding anhydridesprior to their contact with the hydrogenation catalyst in the reactionzone.

In accordance with a preferred embodiment of this invention, a feedcompound, such as one of maleic acid, succinic acid, maleic anhydride,succinic anhydride, or mixtures of any of the foregoing, either with orwithout butyrolactone, is reacted, in the vapor phase, with hydrogen atelevated temperatures in the presence of a Cu-Pd or Cu-Pt catalyst,preferably the former. In conducting this reaction, the temperature thatis employed therein can vary between about 150° C. and 350° C., andpreferably between 180° C. and 330° C. Hydrogen is supplied to thereaction zone in a stoichiometric excess, preferably in such a quantitythat the molar ratio of hydrogen to the anhydride is in excess of 5:1and as high as 200:1 or even higher. The reactants are passed to thecatalytic zone in the vapor phase, the rate of vaporization beingsusceptible to careful control, such as through the use of a vaporizer,and the reaction is carried out at low pressures, which may range fromatmospheric up to about 50 atmospheres. Preferably, however, thepressure is between one and about ten atmospheres.

It is preferred that the contact time between the reactants in thereaction zone in the presence of the instant catalyst be of shortduration, e.g., be in the range of about 2 to 10 seconds, since, forlonger contact times than this, there may result an increased formationof by-products, such as tetrahydrofuran, for example.

The catalyst employed in the process of this invention comprises onecontaining, in the form of free metals, about 3 to about 100% by weight,preferably about 4 to about 30% by weight of an admixture of copper withpalladium or platinum, preferably reduced copper-palladium or reducedcopper-platinum, in which the ratio by weight of copper to palladium orplatinum is about or more than about 10:1 and about or less than about500:1, preferably between about 20:1 and about 250:1. The catalyst maybe in the form of pellets, spheres, extrudate, granules, or any formsuitable for packing a catalyst bed, or it may result from deposition ofreduced Cu-Pd or Cu-Pt on a suitable carrier in a manner well known tothose skilled in the art. It is preferable, however, that the catalystbe reduced with hydrogen at a temperature below about 300° C. tominimize sintering prior to use in the process of this invention.

As previously indicated, the present hydrogenation catalysts arecharacterized by containing either an admixture of copper and palladiumor an admixture of copper and platinum, the former admixture beingpreferred and the one of choice. While palladium and platinum are ofroughly equivalent activity and utility in the present hydrogenationcatalysts, this is only the case under certain circumstances andconditions, owing in part to the nature of the catalyst and its methodof preparation. For example, while there are a number of variousalternative processes available by which to prepare a Cu-Pd catalyst,all of which lead to a catalyst of acceptable quality in terms, e.g., ofits utility herein with respect to activity, selectivity, etc.,nevertheless, this circumstance is not true in the present invention inrespect of the Cu-Pt catalyst, where it has been found that, in order toobtain results for the Cu-Pt catalyst that are equivalent to those bothdesired and obtainable from the Cu-Pd catalyst, the Cu-Pt catalyst mustnot be prepared by many of those procedures by which the correspondingCu-Pd catalyst can be prepared but must be prepared by a specificpreparative technique. For example, the instant Cu-Pt catalyst can beprepared with a utility equivalent to that of Cu-Pd by beingprecipitated from a solution comprising salts of platinum and copper(and, optionally, a carrier such as magnesium silicate, if desired),dried, calcined and then reduced to the elemental form.

However, Cu-Pt catalysts of equivalent activity to that of Cu-Pd, unlikethose comprising Cu-Pd, are not obtained when the following conventionalmethods and procedures are employed to prepare such Cu-Pt catalysts:

(1) Dip impregnation -- wherein a preformed catalyst support is dippedinto a hot concentrated solution of copper and platinum salts, thendried, calcined, and reduced.

(2) Dip impregnation -- wherein the preformed catalyst support is addedto a diluted copper and platinum salt solution, and the unabsorbed saltsolution is then filtered and then recycled, this procedure beingrepeated several times. The impregnated support is then dried, calcined,and reduced.

(3) Impregnation by vacuum stripping -- wherein a mixture of a catalyticmetal salt solution and a catalyst support therefor are first vacuumstripped to dryness, then calcined, and reduced.

(4) Physically blending -- wherein solid salts of the catalytic metalsare physically blended with a catalyst support, and then calcined andreduced.

A preferred procedure for the prior reduction of the Cu-Pd or Cu-Ptcatalyst is as follows:

First of all, an admixture of copper oxide and palladium oxide orplatinum oxide, wherein the ratio of copper to palladium or platinum ispreferably between 20:1 and 250:1, is heated to about 140° C. under aninert atmosphere, e.g., that of nitrogen. Hydrogen is then slowly addedto the system at a rate such as to avoid a build-up of temperaturesabove 300° C. within the catalyst bed. The gas flowing over the catalystbed is gradually enriched with hydrogen as the temperature is slowlyraised to 300° C. At this temperature, the gas may be pure hydrogen. Thecatalyst is then held at this temperature until no further formation ofany water of reduction is observed, whereupon the catalyst may then beused in the present process for producing butyrolactone.

As noted, the present catalyst can be used in a number of differentforms, the choice of which is dependent upon whether or not the processof the present invention is carried out in a fixed bed reactor, or witha fluidized bed reactor, since the present catalyst can be adapted tosuit either of these purposes.

In addition, the present catalyst can also be supported by variouscarriers conventionally used in standard hydrogenation reactions. Arepresentative, non-limiting list of such carriers, which is notintended by any means to be exhaustive, includes such materials asmagnesium silicate, silica gel, kieselguhr, alumina, asbestos, pumice,and those crystalline aluminosilicate materials known in the art asmolecular sieves. Better results and less side reactions are obtained,however, with the non-acidic carriers; hence, non-acidic carriers arethe preferred carriers for purposes of this invention, especially thoseof high surface area. These non-acidic carriers include magnesiumsilicate, silica gel, and asbestos. When a carrier is used, thepreferred range of copper-palladium, or copper-platinum content in theoverall catalyst is about 5-40% by weight.

The process for producing butyrolactone that is contemplated hereincomprises, as noted, catalytic hydrogenation of a suitable feed compoundin the presence of a Cu-Pd or Cu-Pt catalyst. Any reasonably pure gradeof any of the aforementioned feedstocks or mixtures thereof is operable,the only precaution being necessary being that of insuring that thefeedstock in question does not contain any materials that would poisonthe present catalyst. It is well known, for example, that materials suchas halogens and many of the compounds containing same, as well as manynitrogen-and sulfur-containing compounds, are harmful to the activity ofhydrogenation catalysts. Such materials, therefore, are preferablyavoided in carrying out the process of the present invention. As noted,the reactants are passed to the catalytic zone in the vapor phasewhereupon the reaction is effected at low pressures, ranging fromatmospheric and upwards to about 50 atmospheres, preferably between oneand about ten atmospheres.

Owing to the high selectivity of the present Cu-Pd and Cu-Pt catalysts,throughout the range of reaction conditions noted above, the reactionproceeds essentially to almost complete conversion of feedstock tobutyrolactone with only moderate amounts of by-products formed such astetrahydrofuran and butanol, each of which is obtained generally inminor amounts totalling about 2 to about 10 mole-percent of feedstockcharged.

The invention will be further illustrated (but is not limited) by thefollowing examples in which the quantities of reactants recited are byweight unless otherwise indicated. The feed rate, where given in theexamples, is in parts of the feedstock per hour per volume of catalystbed. The temperature of the catalyst bed in each example is the highesttemperature observed in the catalyst bed. In the examples, the over-allmaterial balance was substantially quantitative. The term "conversion",wherever used in the examples, is defined as the percentage of startingmaterial consumed in the reaction. The term "selectivity", wherever usedin the examples, is defined as the percentage of butyrolactone producedas compared to the total amount of starting material consumed. The metalcontent of the catalyst described in the Examples, unless otherwisestated, is in terms of elemental metal.

EXAMPLES EXAMPLE 1 Catalyst Preparation

Respective solutions of 0.5 g. (0.0022 moles) of palladium nitrate in100 ml. of water and a solution of 0.33 g. (0.001 moles) of platinumammonium chloride in 100 ml. of water were each mixed with a solution of80 g. (0.33 moles) of cupric nitrate trihydrate in 200 ml. of water. Ineach of the resulting solutions was slurried 79 g. of magnesiumsilicate. A solution prepared from 70 g. (0.66 moles) sodium carbonatein 200 ml. water was slowly added to each solution to precipitate therespective catalyst precursors. Each of the resultant slurries wasfiltered and washed with 1 liter of water in small portions. Afterdrying at 200° C. for two hours and calcining at 450° C. for 5 hours, 90g. of Cu-Pd catalyst powder, and 88 g. of Cu-Pt catalyst powder wasobtained, whose oxides contained, as free metals, 21% copper and 0.3%palladium and 21% copper and 0.2% platinum, respectively. The resultingcalcined catalyst powders were tableted in 1/4 inch diameter pellets.

EXAMPLE 2

A stainless steel reactor tube with an internal diameter of 1 inch and alength of 12 inches was packed with 55 g. of the Cu-Pd catalyst ofExample 1. The catalyst was reduced over a 6 hour period at 150°-250° C.using 25% hydrogen in nitrogen, introduced intermittently until therewas little exotherm, whereupon the hydrogen concentration was increasedto 100% and the temperature raised to 300° C. for 2 hours. A feed of100% maleic anhydride was carried through the reactor by a hydrogenstream through a vaporizer at 130°-190° C. The rate of vaporization wascontrolled by varying the temperature of the vaporizer. Maintaining thereactor at 285°-290° C. and the feed rate at 8 ml. per hour, theconversation was 92% and the selectivity was 95%.

EXAMPLE 3

A catalyst containing 10% copper and 0.1% palladium was used inequipment similar to that described in Example 2. At 240°-245° C., witha feed rate of 6 ml. per hour, the conversion was 97% and theselectivity was 96%.

EXAMPLE 4

A catalyst containing 6% copper and 0.05% palladium was used in similarequipment as described in Example 2. At 255°-260° C., with a feed rateof 7 ml. per hour, the conversion was 100% and the selectivity was 95%.

EXAMPLE 5

A catalyst containing 20% copper and 0.47% palladium was used in similarequipment as described in Example 2. At 260°-265° C., with a feed rateof 12 ml. per hour, the conversion was 96% and the selectivity was 91%.

EXAMPLE 6

A catalyst was prepared by the procedure of Example 1, using 12% copperand 0.1% palladium on a carrier compound of kieselguhr rather than ofmagnesium silicate, and employed in the standard equipment described inExample 2. At 275° C., with a feed rate of 7 ml. per hour, theconversion was 96% and the selectivity was 93%.

EXAMPLE 7

A catalyst was prepared by the procedure of Example 1 using 21% copperand 0.3% palladium on silica gel as carrier, and employed in thestandard equipment described in Example 2. At 255° C., with a feed rateof 8 ml. per hour, the conversion was 98% and the selectivity was 92%.

EXAMPLE 8

The catalyst was prepared as in Example 1, except for the fact thatcopper was used with 1% palladium and no support was utilized. Analysisof the catalyst pellets before reduction gave 79% copper and 1%palladium. This catalyst was used in the same equipment as described inExample 2 at 280° C., with a feed rate of 6 ml. per hour. The conversionwas 91% and the selectivity was 93%.

EXAMPLE 9

This example was conducted in the same manner as described in Example 2,except for use of 50% maleic anhydride in butyrolactone as the feed.With the feed rate of 16 ml. per hour, the conversion was 92% and theselectivity was 92%.

EXAMPLE 10

This example was conducted in the same manner as described in Example 2,except for use of a mixture of 50% maleic anhydride and succinicanhydride as feed. With the feed rate at 8 ml. per hour, the conversionwas 95% and the selectivity was 93%.

EXAMPLE 11

A catalyst containing 15% copper and 0.2% nickel was used in similarequipment to that described in Example 2. At 305°-310° C., with a feedrate of 8 ml. per hour, the conversion was 92% and the selectivity was70%.

EXAMPLE 12

A catalyst containing 27% copper on magnesium silicate (with no othercatalytic metal present) was used in similar equipment to that describedin Example 2. At 290°-295° C., with a feed rate of 4 ml. per hour, theconversion was 83% and the selectivity was 98%.

EXAMPLE 13

A catalyst containing 0.2% palladium on magnesium silicate (with noother catalytic metal present) was used in equipment similar to thatdescribed in Example 2. At 250° C., with a feed rate of 7 ml. per hour,the conversion was 95% and the selectivity was 21%.

EXAMPLE 14

The Cu-Pt catalyst of Example 1, containing 21% copper and 0.2%platinum, was used in equipment similar to that described in Example 2.At 305° to 310° C., with a 14 ml./hr. feed rate of 50% maleic anhydridein butyrolactone, the conversion was 92% and the selectivity was 96%.

EXAMPLE 15

A catalyst containing 21% copper and 0.2% ruthenium was used inequipment similar to that described in Example 2. At 285° to 290° C.,with an 11 ml./hr. feed rate of 50% maleic anhydride in butyrolactone,the conversion was 81% and the selectivity was 74%.

EXAMPLE 16

A catalyst containing 21% copper and 0.2% rhodium was used in equipmentsimilar to that described in Example 2. At 290° C. and with an 8 ml./hr.feed rate of 50% maleic anhydride in butyrolactone, the conversion was92% and the selectivity was 42%.

In the following Examples 17-20, the catalyst described was prepared inaccordance with the procedure set forth in Example 1.

EXAMPLE 17

A catalyst containing 10% copper and 0.1% platinum was used in equipmentsimilar to that described in Example 2. At 280°-285° C., with a 12ml./hr. feed rate of 50% maleic anhydride in butyrolactone, theconversion was 94% and the selectivity 95%.

EXAMPLE 18

A catalyst containing 6% copper and 0.05% platinum was used in equipmentsimilar to that described in Example 2. At 280° C-285° C, with a 6ml./hr. feed rate of 100% maleic anhydride, the conversion was 100% andthe selectivity 95%.

EXAMPLE 19

A catalyst containing 12% copper and 0.1% platinum was used in equipmentsimilar to that described in Example 2. At 290°-295° C, with a 6 ml./hr.feed rate of 100% maleic anhydride, the conversion was 94% and theselectivity 93%.

EXAMPLE 20

A catalyst containing 20% copper and 0.5% platinum was used in equipmentsimilar to that described in Example 2. At 285°-290° C., with a 7ml./hr. feed rate of 100% maleic anhydride, the conversion was 98% andthe selectivity 91%.

EXAMPLE 21 Preparation (partially by vacuum stripping) and Use of aCu-Pt Catalyst (Comparative Example)

The catalyst was prepared by dissolving 160 grams of cupric nitrate in300 ml. of water and adding 158 g. of magnesium silicate to make aslurry. A solution prepared from 140 g. of sodium carbonate in 300 ml.of water was slowly added to precipitate the catalyst precursor. Theslurry was filtered and washed with 1 liter of water in small portions.After drying at 200° C. for two hours and calcining at 450° C. for 5hours, 180 g. of catalyst powder was obtained containing 21% copper asthe oxide. The resulting calcined catalyst powder was tableted in 1/4inch diameter pellets. 100 g. of these catalyst pellets were charged toa 500 cc flask, and a solution of 0.4 g. of platinum ammonium chloridein 100 cc. of water was added. This mixture was stirred, then the waterwas vacuum stripped at 70° C. and 1 mm Hg vacuum to dryness. The driedcatalyst pellets containing the absorbed platinum salt were calcined at450° C. for 5 hours and then reduced as per Example 2. The catalystcontaining 21% copper and 0.2% platinum was then used in equipmentsimilar to that described in Example 2. At 285° C. to 290° C. with afeed rate of 5 ml./hr., the conversion was 98% and the selectivity 35%.

The above results would have shown even poorer selectivity if both thecopper and platinum had been fully impregnated into the support by thevacuum stripping technique, or by the various other conventional dipimpregnation, or physical blending, techniques previously describedabove. Thus, this comparative example illustrates that specialpreparative means and a specific method are necessary in order for thepresent Cu-Pt catalyst to be obtained of a catalytic quality equivalentto that of the present Cu-Pd catalyst.

We claim:
 1. A process for producing gamma-butyrolactone, comprisingcontacting a feed compound selected from the group consisting of maleicacid, succinic acid, maleic anhydride, succinic anhydride, mixturesthereof, and mixtures of any of the foregoing with butyrolactone; in thevapor phase, with a stoichiometric excess of hydrogen at a pressureranging from atmospheric to about 50 atmospheres and at a temperaturebetween about 150° C. and about 350° C. in the presence of an elementalcopper-elemental metal catalyst comprising about 3 - 100 percent byweight of an admixture of elemental copper and an elemental metalselected from the group consisting of palladium and platinum, the weightratio of copper to said elemental metal ranging from about 10:1 to about500:1, the rest of said admixture being a non-acidic carrier.
 2. Aprocess according to claim 1 wherein the weight ratio of copper to saidelemental metal ranges from about 20:1 to about 250:1.
 3. A processaccording to claim 1 wherein the molar ratio of hydrogen to said feedcompound is in excess of about 5:1.
 4. A process according to claim 1wherein the non-acidic carrier is selected from the group consisting ofmagnesium silicate, silica gel and asbestos.
 5. A process according toclaim 1 wherein said elemental copper-elemental metal catalyst iselemental copper-elemental palladium.
 6. A process according to claim 1wherein said catalyst comprises about 5 to about 40% by weight of saidadmixture.
 7. A process according to claim 1 wherein said elementalcopper-elemental metal catalyst is elemental copper-elemental platinum.8. A process according to claim 7 wherein the weight ratio of elementalcopper to said elemental platinum is from about 20:1 to about 250:1. 9.A process according to claim 1 wherein said feed compound is maleicacid.